Adaptive Cruise (i.e., speed) Control (ACC) systems operate much like conventional Cruise Control systems, with the added capability of being able to sense in-path vehicles and to slow the ACC equipped vehicle in response. An ACC equipped vehicle thereby allows its operator to automatically control the vehicle speed, as with conventional Cruise Control, without the necessity of having to deactivate and reactivate control whenever slower traffic is encountered.
As is well known in the art, existing ACC methods and systems use a forward looking range sensor such as radar to sense an in-path vehicle (which may also be referred to as a sensed target or primary target). Based on the radar sensor information, such ACC methods and systems then determine the range and relative velocity (or range rate) of the sensed in-path path vehicle. Using the range and range rate, the speed of the ACC equipped vehicle is controlled to maintain a selected following interval between the ACC equipped vehicle and the sensed in-path vehicle. The following interval, also referred to a headway, is set at a default value upon activation of such ACC methods and systems, and is modifiable by the vehicle operator within a predefined range of values. The speed of the ACC equipped vehicle is typically controlled by automatic control of the vehicle throttle actuator. In more advanced ACC methods and systems, vehicle speed may also be controlled by automatic control of vehicle brake actuators. Such ACC methods and systems have the ability to apply a moderate degree of braking to the vehicle to achieve further vehicle deceleration (i.e., in addition to vehicle deceleration achieved via throttle control) in response to an in-path vehicle.
Thus, existing ACC methods and systems must provide the vehicle operator with not only the ability to activate the vehicle ACC system, but to select a following interval as well. To do so, however, existing ACC methods and systems employ two vehicle operator switches, one for activating the ACC system and another for adjusting a headway setting. Moreover, in a vehicle equipped with a standard speed control systems, when an ACC system is added to the vehicle, an additional vehicle operator switch must be provided for adjusting a headway setting.
As a result, there exists a need, in an ACC system for a vehicle, for a method and system for providing a headway function to the ACC system activation switch. Such a method and system would determine whether the adaptive speed control activation switch has been actuated, and, if so, determine whether the adaptive speed control system is already active. If the adaptive speed control system is active, such a method and system would then control a headway function of the adaptive speed control system in response to the actuation of the adaptive speed control activation switch. Such control would include adjusting the headway setting of the adaptive speed control system. By providing an adaptive speed control activation switch with such dual capability, such a method and system would eliminate the need for two separate vehicle operator switches, thereby reducing cost.